Tetsu is the official shipwright aboard Ching's Glory. Still in his early teens, he is remarkably skilled with mechanics and invention. He was an orphan raised by members of an engineers’ guild in the Fire Nation, though his hazel eyes imply that he has Earth Kingdom blood. His mind rarely stops working on new designs for new creations, and for this reason he is often jotting down notes and diagrams on pieces of scrap paper that he keeps tucked into his belt. The sheer quantity and revolutionary nature of his designs struck even his fellow engineers as bizarre, and it was not until the opportunistic Ching snatched him up that he was able to truly give his creativity room to stretch.

Tetsu is a boy of few emotions, and almost always speaks in a monotone, and never uses contractions. He sees his machinations as signs of true progress, and is disdainful of people who he believes to “live in the past.” He is reluctant to spring into battle, but when he does he employs a plethora of offensive gadgets, ranging from a hand-held bola launcher to miniature smoke bombs. He also uses a steam-powered “jetpack” to provide aerial support, though the device is very high-maintenance and prone to backfires.

Tetsu regards his crewmates, especially Gai Dao and Pao, as lowbrow rabble-rousers who serve no greater purpose than carrying heavy equipment. He does what Ching says mostly because she is, frankly, the most dangerous human he has ever met and because she gives him plenty of good work.

Tetsu may later develop a hilariously OOC crush on Princess Nikiru for the sole purpose of contrasting him with Yi Lin.

Tetsu’s goggles, which he needs to read properly, are equipped with multiple lenses that flip down to give him better magnification, filter out sunlight, et cetera. When they’re all up, he looks like he’s wearing a miniature version of those things you put on at the eye doctor’s.